Modern civil construction makes extensive use of pre-stressed, precast concrete beams. Parking garages and other buildings can be quickly, economically and profitably constructed using precast, pre-stressed beam members. Double tee beam shapes are widely used; typically, these members can have a top flange, a total flange-and-web depth of up to 48 inches, and a length of 60 feet.
To reduce floor-to-floor building height without losing necessary strength in the structural beam members, the web ends of these tees or double tee members can be provided with “daps.” A “dap” design provides a recess in the lower corners of the beam web. When the beam is installed in the building, this recess or notch mates with a haunch, pilaster or other supporting structure, and the mating arrangement accordingly reduces the floor-to-floor height of the building. Proper steel reinforcement of the dapped beam ends is important.
Historically, these precast, pre-stressed concrete members were manufactured by specialized manufacturing or pre-casting companies, and then finished beams were sold to the building construction contractor on an as-needed, where-needed basis. But the pre-casters were required to assemble and weld their own steel reinforcing systems for the beams and other members they are casting. The proper and economical fabrication of the dap reinforcing structures was particularly difficult, time consuming and expensive. Economies of scale and mass production were only minimally available to the pre-caster who manufactures his own reinforcing assemblies. And if special steel rod sizes or other steel shapes were found to be desirable from a design standpoint, the manufacture and purchase of such special shapes can be prohibitively expensive if only a few are needed.
In order to alleviate the difficulties of reinforcing the daps, pre-manufactured steel reinforcing assemblies, especially adapted for effective use with dapped beam ends, were developed. These reinforcing assemblies are installed into the double tee daps when the double tees are cast.
The dimensions of the dap reinforcing assemblies are typically finalized and manufactured after the structural engineer has completed his design of the double tee and associated daps. If the structural engineer makes changes to the double tee or dap design after the reinforcing assemblies have been manufactured, the dap assemblies will need to be discarded and remanufactured to reflect the changes made.
Additionally, due to the fact that these dap reinforcing assemblies are designed and built for each project, any unused or spare assemblies remaining at the end of the project have no value and are discarded or recycled.
Accordingly, there is a need for dap reinforcing assemblies that allow for adjustments to accommodate design changes made to a double tee dap by a structural engineer during the course of a project to reduce waste and cost.
Additionally, there is a need for dap reinforcing assemblies that allow for adjustments to create versatility so that the same dap reinforcing assemblies can be used on multiple projects.